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Christophe Nicolet

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Publications associées (48)

Hydraulic design of the diaphragm’s orifice at the entrance of the surge shaft of FMHL pumped-storage power plant

Giovanni De Cesare, Christophe Nicolet, Rafael Xavier Meriade Duarte, Fadi Hachem

The surge tank located at the upstream head of penstocks and shafts of hydropower plants is an effective measure to protect the headrace tunnels against high pressure fluctuations. It reflects the transient pressure waves that are generated by the variatio ...

TPU2013

Modeling and control of large salient-pole synchronous hydro generators and stability issues in isolated production mode

Basile Kawkabani, Alexander Schwery, Christophe Nicolet

This paper presents the modeling, simulation and analysis of the dynamic behavior of a hydroelectric power plant of 2x343 MVA including hydraulic system, electrical installations, rotating inertias and control systems. First, the modeling of the electrical ...

Ieee2013

Simulation of water column separation in Francis pump-turbine draft tube

François Avellan, Christophe Nicolet, Sébastien Alligné

The paper presents the modelling, simulation and analysis of the transient behaviour of a 340 MW pump-turbine in case of emergency shutdown in turbine mode with focus on possible draft tube water column separation. The model of a pumped storage power plant ...

International Association For Hydraulic Research2012

Parametric study of water column separation in Francis pump-turbine draft tube

François Avellan, Christophe Nicolet, Sébastien Alligné

The paper presents the modelling, simulation and analysis of the transient behaviour of a 340 MW pump-turbine in case of emergency shutdown in generation mode with particular attention to the possible draft tube water column separation. First, the model of ...

Soc Hydrotechnique France2012

Optimization of the Start-up Time of a Variable Speed Pump-Turbine Unit in Pumping Mode

Basile Kawkabani, Jean-Jacques Simond, Christophe Nicolet, Yves Pannatier

This paper presents the start-up and synchronization procedures of large variable- speed pump-turbine units in pumping mode. These procedures applied to a doubly-fed induction motor-generator with three-level voltage source inverters VSI cascade in the rot ...

2012

Modeling of Unsteady Friction and Viscoelastic Damping in Piping Systems

François Avellan, Christophe Nicolet, Andres Müller, Christian Landry

In real systems, the phenomena, such as pipe-wall viscoelasticity, unsteady friction or fluid structure interaction induce additional damping and dispersion of transient pressure waves than that defined by classical waterhammer. In this paper, unsteady fri ...

International Association For Hydraulic Research2012

Cavitation influence on hydroacoustic resonance in pipe

François Avellan, Christophe Nicolet, Nicolas Ruchonnet, Sébastien Alligné

In pipe systems, pressure and flow fluctuations below cutoff frequency propagate as plane waves along pipes. Depending on the pipe length and propagation velocity, resonance leading to high amplitude pressure fluctuation may occur. At low pressure, cavitat ...

Elsevier2012

On the upper part load vortex rope in Francis turbine: Experimental investigation

François Avellan, Christophe Nicolet, Amirreza Zobeiri, Pierre Maruzewski

The swirling flow developing in Francis turbine draft tube under part load operation leads to pressure fluctuations usually in the range of 0.2 to 0.4 times the runner rotational frequency resulting from the so-called vortex breakdown. For low cavitation n ...

International Association For Hydraulic Research2010

Hydroacoustic Simulation of Rotor-Stator Interaction in Resonance Conditions in Francis Pump-Turbine

François Avellan, Christophe Nicolet, Nicolas Ruchonnet, Sébastien Alligné

Combined effect of rotating pressure field related to runner blade and wakes of wicket gates leads to rotor stator interactions, RSI, in Francis pump-turbines. These interactions induce pressures waves propagating in the entire hydraulic machine. Superposi ...

International Association For Hydraulic Research2010

Influence of the Francis turbine location under vortex rope excitation on the hydraulic system stability

François Avellan, Basile Kawkabani, Jean-Jacques Simond, Philippe Allenbach, Christophe Nicolet, Sébastien Alligné

Hydroelectric power plants are known for their ability to cover variations of the consumption in electrical power networks. In order to follow this changing demand, hydraulic machines are subject to off-design operation. In that case, the swirling flow lea ...

2009

Numerical Simulation of Nonlinear Self Oscillations of a Full Load Vortex Rope

François Avellan, Christophe Nicolet, Nicolas Ruchonnet, Pierre Maruzewski, Vlad Hasmatuchi, Sébastien Alligné

Self excited instabilities or oscillations of a cavitating full load vortex rope occur due to an interaction between the gas volume and the acoustic waves. From the onset of the oscillations, the amplitudes grow until they reach a maximum, called the “limi ...

2009

Experimental Evidence of Hydroacoustic Pressure Waves in a Francis Turbine Elbow Draft Tube for Low Discharge Conditions

François Avellan, Christophe Nicolet

The complex three-dimensional unsteady flow developing in the draft tube of a Francis turbine is responsible for pressure fluctuations, which could prevent the whole hydropower plant from operating safely. Indeed, the Francis draft tube is subjected to inl ...

2009

Influence of the vortex rope location of a Francis Turbine on the hydraulic system stability

François Avellan, Basile Kawkabani, Jean-Jacques Simond, Philippe Allenbach, Christophe Nicolet, Sébastien Alligné

International Association For Hydraulic Research2008

Transient Behavior of variable speed pump-turbine units

François Avellan, Basile Kawkabani, Alexander Schwery, Jean-Jacques Simond, Christophe Nicolet, Yves Pannatier

This paper presents the modeling, simulation and analysis of the dynamic behavior of a fictitious 2x320 MW variable speed pump-turbine power plant including hydraulic system, electrical installations, rotating inertias and control systems. First, the model ...

International Association For Hydraulic Research2008

One-Dimensional Analysis of Full Load Draft Tube Surge

François Avellan, Christophe Nicolet, Mohamed Farhat

One-dimensional stability analysis of a hydraulic system composed of a penstock, a runner, and a draft tube was carried out to determine the cause of the full load draft tube surge. It is assumed that the cavity volume at the runner exit is a function of t ...

2008

One-dimensional analysis of full load draft tube surge

François Avellan, Christophe Nicolet, Mohamed Farhat

A previous report by the present authors [1] clarified the diffuser effect of the draft tube and the effects of swirl in the runner downstream on the hydraulic instabilities in power generation plants. The present study was intended to study the effect of ...

International Association For Hydraulic Research2008

Transient Behavior of Variable Speed Pump-Turbine Units

François Avellan, Basile Kawkabani, Alexander Schwery, Jean-Jacques Simond, Christophe Nicolet, Yves Pannatier

2008

Turbine Speed Governor Parameters Validation in Islanded Production

François Avellan, Basile Kawkabani, Jean-Jacques Simond, Philippe Allenbach, Christophe Nicolet, Bob Greiveldinger

The transient behavior of hydroelectric power plants is of high interest for ensuring stability of islanded electrical power networks. Therefore, it is suitable to determine and validate the set of parameters of a turbine speed governor using a realistic s ...

2007

Modeling and Numerical Simulation of a Complete Hydroelectric Production Site

François Avellan, Jean-Jacques Simond, Philippe Allenbach, Christophe Nicolet

For many years the EPFL Laboratory for Electrical Machines develops SIMSEN, a numerical software package for the simulation in transient and steady-state conditions of electrical power systems and adjustable speed drives, having an arbitrary topology. SIMS ...

2007

High-Order Modeling of Hydraulic Power Plant in Islanded Power Network

François Avellan, Basile Kawkabani, Jean-Jacques Simond, Philippe Allenbach, Christophe Nicolet, Bob Greiveldinger

Numerical simulations of the transient operation of an islanded power network subject to load rejections are performed. The islanded power network case study consists of a 1-GW hydroelectric power plant featuring four generating units, a long penstock, and ...

IEEE Institute of Electrical and Electronics Engineers2007

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